The alarming disproportionate impact of the COVID-19 pandemic on underserved as well as medically and socially vulnerable populations requires generating new knowledge to help mitigate its effects. We will address existing knowledge gaps in two specific aspects of COVID-19 mitigation strategies – return of SARS-CoV-2 test results and COVID-19 vaccination - through synergistic application of community-engaged research and novel informatics approaches in collaboration with our community partners: the Association to Benefit Children, Project New Yorker, and the Chinese American Planning Council. In addition, for this Supplement, which builds upon our RADx-UP Phase 1 project, Reaching Communities through the Design of Information Visualizations for Returning COVID-19 Results (ReDIVis Toolbox: RCR), we have formed a strategic partnership with the New York City Community Engagement Research Alliance (NYCEAL) Against COVID-19 Disparities to leverage the evidence-informed communication resources of CEAL. The overall goal of Reaching Communities through the Design of Information Visualizations Toolbox (ReDIVis Toolbox: Vaccination) is to decrease health disparities related to COVID-19 vaccination in underserved and vulnerable populations by enabling widespread use of culturally congruent and health literate infographics to decrease vaccine hesitancy and improve vaccine uptake in a manner that is comprehensible, informs decision making, and motivates appropriate behaviors. Our specific aims build upon: (a) our accomplishments to date in our RADx-UP Phase 1 project; (b) the rich resources of the Visualization Design Studio of the Precision in Symptom Self-Management (PriSSM) Center, the qualifying grant for this emergency competitive revision in response to NOT-OD-21-101; and (c) partnership with NYCEAL through a subcontract with New York University. We will use a mixed-methods design to achieve the following specific aims: (1) Advance understanding of the factors that influence comprehension and use of the results of SARS-CoV-2 diagnostic and antibody testing, and COVID-19 vaccine hesitancy and uptake in underserved and vulnerable populations; (2) Collaborate with underserved and vulnerable populations to design infographics for returning the results of SARS-CoV-2 diagnostic and antibody testing, and for addressing vaccine hesitancy and uptake in a format that maximizes comprehension, informs decision making, and motivates action; and (3) Develop, implement, evaluate, and disseminate the ReDIVis Toolbox to create infographics for returning the results of SARS-CoV-2 diagnostic and antibody testing and addressing vaccine hesitancy and uptake. ReDIVis Toolbox: Vaccination directly responds to multiple areas of interest including strategies to communicate culturally and linguistically appropriate information about COVID- 19 vaccines to foster vaccine confidence and acceptance, and dissemination and communication strategies to amplify or extend the reach of the...